Process for manufacturing a lead accumulator



Patented Mar. 2, 19 26.

-um'rlzn STATES PATENT OFFICE.

KANESHI KAWAKAHI, OF HONGO-KU, TOKYO, JAPAN;

' PROCESS FOR MANUFACTURING A LEAD ACCUMULATOR.

No Drawing.

To all to]: om it may concern:

Be it known that I, KANssnI KAWAKAMI,

a subject of the Emperor of Japan, residing at No. 3 Komagome-Akebono-Cho, Hongo- Ku, Tokyo, Japan, have invented a new and useful Process for Manufacturing a Lead Accumulator, of which the following is a specification.

This invention relates to a process for manufacturing a porous lead for lead accumulators or of a porous lead alloy from' alead alloy. For example, an alloy of lead and potassium, lead and magnesium, lead, potassium and mercury, lead, magnesium and calcium or-its compounds, lead,antimony and mercury, and of other alloy-of lead with one or more metals in the magnesium group, the alkali group, the alkaline earth group, the arsenic group,'the tin group,-

or the aluminum group. The method of producing such porosity in the lead. or alloy consists in driving out a tion of the alloy by mec anical treatment, such as treatment in a centrifugal separator, while heating the said alloy to a temperature below its'melting point and while keeping the same at that temperature. The objects of this invention are, first, to obtain a lead accumulator of high electrical efliciency and of long life; second, to obtain the same of high weight efiiciency.

In'carr ing out the invention, I take as an examp e, an alloy, in a shape of a plate,

ribbon, rod, or like desired shape, of a c0m position consisting of 93 per cent of'lead, 1 per centof mercury and '6 per cent of antimony,'respectively, in weight. A frame or grid, consisting of lead, or of an alloy of 99 per cent of; lead and 1 percent of mercury,.in which the aforesaid alloy is cast, or fused therein, ma be taken instead of the foregoing plate of t e alloy. Such plate of the alloy is heated, .in a centrifugal separator, for 20 130-30 minutes by means .of an electric current to below its melting point,

that is to say, to about a temperature 300- 0., until the-said plate is :uniforn'gl'y heated,-

and is then submitted to mechanical treatment, suchas treatment in a centrifugal separator, keeping the same at said temperature. After a few minutes of such-treat .ment a melted alloy, constituting a eutectic )r eutectics, contained therein, consisting of '13 per cent of'lead and 87 per cent of anti mony in weight, -:is dri en off and the remaining product is a porousmetallic body artlyv melted por- Application filed October 3, 1921. Serial No. 505,177.

consisting of about 97.8 cent. of lead,

about 1.8 per cent'of mercury and about 0.4.

per cent of antimony in weight. When the.

framed alloy plate is treated in the like man'- ner, lliave. found that no change in structure of the frame or grid of'lead, or of an alloy of lead and mercury, takes place. The said porous product thus obtained may be used as a battery plate, in that condition according to its shape, or may be set in aframc or grid, by being cast or fused therein, and submitted to treatment and formation such as commonly applied heretofore to an ordinary electric accumulator plate.

In carrying out this invention the following alloys, may also be used instead of the aforesaid alloy, and whose proportion of constituents, temperature applicable to them,

280 C., constitution of eutectic 97% of lead,

about 2.9% of magnesium and about 0.1%

of calcium, or its compound, finished prodnot of about 100% of lead; V

Alloy of 99.4% of lead and 0.6% of potassium, application of temperature about 300 -C., constitution of eutectic about 98.2% of lead and about 1.8% of p'otassiuni, finished product-of-about 100% of lead; The proportions of the constituents for the alloy and the temperature to be applied,

may be varied slightly, so as to obtain finished porous products of a fine, or of a coarsestructure, according to requirements 100.

in use. 7 V

In the separating process of the given example, where the initial alloyed plate 'con- I tained lead and 'antimony, very thin films of antimony are apt to remain on the inner surfaces of the finished porous product, but,

if mercury was added in the said lead-antimony alloy, then the retainingaction of the antimony films is considerably reduced. The porous metals thus prepared are particularly suitable as batteryplates.

The effect of the mercury contained in the lead alloy is to increase considerably the mechanical strength of the alloy, and from 0.5 to 5.0 per cent of mercury is very particularly advantageous in this respect. Moreover, in the aforesaid separating process, this alloy used for the frame or grid, etc., causes no change in its structure, and is in this respect like pure lead; but its strength is much higher than the latter.

Theexistence of mercury in the grain of the lead as a solid solution causes an increase in the strength of the porous lead alloy. This is not only advantageous for the battery plate from a mechanical point of view, but also advantageous from an electrochemical point of view in that the mercury contained in the lead battery plate suppresses local discharge and other detrimental actions.

Besides the foregoing actual example, it is possible to obtain a porous lead, or a porous lead alloy, from binary or plural elements, consisting of lead with a metal, or metals of the magnesium group, the alkali group, the tin group, the arsenic group, the alkaline earth group and the aluminium group, by the same method as described above.

In the method of forming the porous body of lead, as traces of every constituent may remain in the lead body after the alloy constituting the eutectic is driven off, its efl'ect varies according to the different alloy employed; thus, when it is desired to entirely exclude antimony, the porous lead body, produced by the present process, may be formed with an alloy of lead and magnesium, or potassium, and it is commonly known that magnesium or potassium remaining therein,is advantageous for making a battery plate, especially when used with a sulphuric compound, that is to say, a considerable advantage may be obtained by employing magnesium or potassium in such porous lead.

The battery plates made in accordance with the process herein described have an extremely large capacity as compared with those manufactured by the ordinary methods. Moreover, the adhesion between the frames or grids, or conducting members and the finished porous products, or active material's, and also the cohesion between the active material particles are excellent and, further, the local discharge and other detrimental actions are suppressed. Therefore, the electric accumulator constructed with such porous plates has an extremely high weight efiiciency, high electrical efiiciency and long life, by virtue of the toughness and high qualities of the active materials.

So far as it does not depart from the esscntial idea of this invention, similar or equivalent steps or stages in the procedures of the process as described, which can bring about the same effect, may be carried out without departing from the spirit of this invention.

What I claim is 1. A battery element comprising a solid solution of a small'percentage of mercury in a large percentage oflead alloyed with a. small percentage of antimony, in the form of a porous plate.

2. A battery element comprising a solid solution of 97.8% of lead, 1.8% of mercury in solid solution with the lead, and .47 2; of antimony alloyed therewith, in the form of a porous plate.

In witness whereof I have hereunto set my hand.

' KANESHI KAWAKALH. 

